President Donald Trump has spoken before Congress plenty of times. But when he delivers his State of the Union speech Tuesday, he'll be standing on unfamiliar political ground: Americans watching the speech distrust him on the economy. An AP-NORC poll this month found that just 39% approve of Trump’s handling of the economy, while 59% disapprove. It's the latest measurement, but it's no outlier, with other surveys showing Trump's economic approval rating underwater. Over the last year, Trump has seen his ratings on the issue sink. That’s a marked contrast from his first term, when he largely broke even or enjoyed broad approval on the economy, even in the Covid-19 downturn, according to the same AP-NORC poll. The public perception that Trump was good for the economy had been a vital political asset. Dating to his first campaign, Trump's business experience and claims of understanding the economy appealed to some voters who disapproved of him over other matters.…